There is a conventionally-proposed technique for detecting a sight line position at which a person gazes and inputting, for example, an operating instruction for an electronic device on the basis of the detected sight line position. A technique disclosed, for instance, in Patent Literature 1 improves the operability and dependability of sight line input by setting a sight line input instruction portion in such a manner as to include an outer region of a displayed image indicative of an input item.
The inventor of the present application has found the following findings. When sight line input is to be applied to a display device installed, for instance, on an instrument panel or center console of an automobile, a significant burden is placed on a driver of the automobile since the driver has to look away from a driving visual field and gaze at a screen targeted for operation. Meanwhile, the technique described in Patent Literature 1 improves the operability and dependability by increasing the size of the input instruction portion. However, the technique is not adequate for solving the above difficulty since it still requires the driver to look away from the driving visual field and gaze at a displayed image.